{
  "bibcode": "2007GCN..6465....1P",
  "body": "D. A. Perley, J. S. Bloom, R. J. Foley, and D. Kocevski (UC Berkeley) \nreport:\n\nOn the night of 2007-04-16 (UT) we performed imaging on the field of \nGRB070412 (GCN 6273), the long burst located approximately 45\" in \nprojection from a nearby early-type galaxy (GCN 6275), using Keck I \n(/LRIS) under poor seeing conditions.  We acquired a total of 113 \nminutes of usable exposure time in I-band and 132 minutes in V-band, \nwith a mid-exposure time of approximately 11:27 UT, 106 hours after the \nBAT trigger.\n\nUsing the astrometrically-corrected XRT position [1] (RA=12:06:10.18, \ndec=+40:08:35.3, uncertainty=2.2\"), we observe a faint source at the \nedge of the uncertainty region in I-band.  This source is not detected \nin V-band.  Calibrating with respect to nearby stars from SDSS, we \ncalculate a magnitude of:\n\nI = 24.6 +/- 0.3\n\nThe V-band limiting magnitude is V > 26.5.\n\nWe note that the same source is also apparent in LBT r' imaging from \nPrieto et al. (GCN 6374) in both their epochs of observation (2.8 hours\nand 8.2 days after the burst), suggesting the source is not transient, \nin which case we place an I-band limiting magnitude of I > 25.0 on any \ntransient source in the XRT error circle.  The red color is suggestive \nof a high-redshift potential host galaxy.  The LBT r' detection would \nplace a firm upper limit on the redshift to be z < 5.9.\n\nImages of the field are located at:\n\nhttp://lyra.berkeley.edu/~dperley/070412/070412keck.png\nhttp://lyra.berkeley.edu/~dperley/070412/070412keckzoom.png\n\nThe low-redshift galaxy has been subtracted using a Sersic model fit in \nthe first image and a median filter in the second (zoom) image.\n\n\n[1] http://astro.berkeley.edu/~nat/swift/xrt_pos.html",
  "circularId": 6465,
  "createdOn": 1180312263000,
  "email": "dperley@astro.berkeley.edu",
  "subject": "GRB 070412:  Deep Keck imaging",
  "submitter": "Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>",
  "eventId": "GRB 070412"
}